1. Field of the Invention
The present invention relates to a carrier apparatus for clamping a work by a two-dimensional rectangular motion of a pair of feed bars to automatically carry the work linearly.
2. Related Art
In a transfer press, there is used a transfer apparatus adapted to automatically carry out the carrying of a work for achieving the labor saving. In this transfer apparatus, a series of operations are carried out which comprising gripping and feeding a work, and releasing it at a position as required by a two-dimensional rectangular motion performed by a pair of feed bars arranged in parallel. In the above-described carrier apparatus, a mechanism for causing the feed bars to effect the rectangular motion is classified into a mechanical system comprising a planet gear, a link, a cam or the like and driven from a driving source of the press, and an independent driving system for independently carrying out each linear motion making use of a servo motor, a cylinder or the like.
However, in the conventional carrier apparatuses described above, in the independent driving system, the apparatus is driven by a driving source such as a servo motor, a cylinder or the like completely independent of a driving source of the press. Therefore, it requires a difficult control such that the servomotor or the cylinder is operated in synchronism with processes of the press. For this reason, in the case where the press is operated at high speeds, it is necessary to operate the carrier apparatus at high speeds to speed up the carrying speed accordingly. However, technical means of high degree is necessary to eliminate even a slight deviation in synchronizing them, and adjustments with high accuracy are necessary, making it very difficult to effect the continuous operation smoothly for a long period of time.
On the other hand, in the mechanical type carrier apparatus, since it is driven by a driving source of the press, the operation of the press can be positively synchronized with the carrier operation of a work. As a typical transfer driving mechanism of the mechanical system, a mechanism using a planet gear has been known, in which the rotation of the driving shaft of the press body is transmitted to a planet gear inscribed with a sun gear through the sun gear within a transfer unit. The planet gear is provided with an eccentric pin, and the locus of the pin is used as a transfer feed amount. In the clamp and unclamp motion of a work, an opening and closing mechanism of feed bars is driven in a manner such that a rack and pinion is rotated by a plate cam mounted on the side of the slide through a link in contact with the cam.
However, the above-described mechanical system has various problems in that the construction is materially complicated in which a turning force input from the press is converted into a series of operations of gripping, feeding and releasing the work; the number of constituent parts considerably increases so that the entire apparatus increases in size and the cost of apparatus increases; and since the construction is complicated, it is difficult to secure the operation at high speeds.